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Mastering Kotlin Essentials

Numeric Conversions and Operations

Explore Kotlin's number handling including literal formatting, numeral systems, and type conversions. Learn arithmetic and bitwise operations, and when to use BigDecimal and BigInteger for precise calculations.

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Underscores in numbers

In number literals, we can use the underscore (_) between digits. This character is ignored, but we sometimes use it to format long numbers for better readability.

Kotlin
fun main() {
    val million = 1_000_000
    println(million) // 1000000
}

Other numeral systems

To define a number using the hexadecimal numeral system, start with 0x. To define a number using the binary numeral system, start with 0b. The octal numeral system is not supported.

Kotlin
fun main() {
    val hexBytes = 0xA4_D6_FE_FE
    println(hexBytes) // 2765553406
    val bytes = 0b01010010_01101101_11101000_10010010
    println(bytes) // 1382934674
}

The Number type and conversion functions

All basic types that represent numbers are subtypes of the Number type.

Kotlin
fun main() {
    val i: Int = 123
    val b: Byte = 123
    val l: Long = 123L
    val n1: Number = i
    val n2: Number = b
    val n3: Number = l
    println("n1: $n1")
    println("n2: $n2")
    println("n3: $n3")
}

The Number type specifies transformation functions: from the current number to any other basic type representing a number.

Kotlin
abstract class Number {
    abstract fun toDouble(): Double
    abstract fun toFloat(): Float
    abstract fun toLong(): Long
    abstract fun toInt(): Int
    abstract fun toChar(): Char
    abstract fun toShort(): Short
    abstract fun toByte(): Byte
}

This means that we can transform each basic number into a different one using the to{new type} function. Such functions are known as conversion functions.

Kotlin
fun main() {
    val b: Byte = 123
    val l: Long = b.toLong()
    val f: Float = l.toFloat()
    val i: Int = f.toInt()
    val d: Double = i.toDouble()
    println("b: $b")
    println("l: $l")
    println("f: $f")
    println("i: $i")
    println("d: $d")
}

Operations on numbers

Numbers in Kotlin support the basic mathematical operations: ...